Bustle pipe for blast furnaces



March 1, 1960 w. ODENDAHL BUSTLE PIPE FOR BLAST FURNACES Filed Jan. 15, 1958 mm mm W N United States Patent 2,926,903 BUSTLE PIPE FOR BLAST FURNACES Wilhelm Odendahl, Gummersbach, Rhinelaud, Germany, assignor to Strico Gesellschaft fur Metallurgie und Warmetechnik m.b.H., Gummersbach, Rhineland, Germany Application January 15, 1958, Serial No. 709,156 Claims priority, application Germany January 29, 1957 6 Claims. c1. 266-30) This invention relates to means for uniformly distributing air to the tuyere system of a blast furnace which preferably is operated with hot air.

In a blast furnace, for reasons of economy and operating technique, it is desirable to attain a symmetric distribution of air. It has already been proposed to divide the bustle pipe, i.e., the means by which air is fed to the tuyeres, by a horizontal partition into two annular or. ring-shaped chambers and to insert in the partition, for the purpose of establishing communication between the two chambers, a plurality of pipe elements the axes. of which lie parallel to the axis of thefurnace. The air issuing from the air main or supply conduit is introduced tangentially into the upper chamber. Since the pipes in the partition extend transversely to the direction of flow in the upper annular chamber, any eifect of the velocity of flow of the air is substantially completely eliminated. The furnace air flows through the pipes in the partition into the lower annular chamber in which any possible pressure differences can be evened out, the air then flowing to the tuyere connections.

By means of the known arrangements of this type, especially when cold furnace air is employed, the causes of an asymmetrical furnace air distribution, to the extent that they are based on the pressure distribution characteristics of the air distributing system, may be substantially compensated for. This advantage, however, is only attained at the expense of a great amount of space and material.

If the blast furnace is operated with hot air, there arises, due to the fact that the peripheral surface area of the divided-chamber bustle pipe is almost twice as large as that of a conventional bustle pipe, an equally great increase in the temperature drop of the air. Because of the tangential introduction of the air into the upper chamber, moreover, the path of the air is twice as long as that in a conventional bustle pipe constructed for radial introduction of air. The air reaching the last tuyere thus is greatly cooled and tends under certain conditions to soiling or clogging of the said last tuyere, whereby the air suppled through the same is greatly decreased. The air distribution is, therefore, again rendered asymmetrical. As a further disadvantage, there arises a pronounced decrease of the temperature of the coke burning at the tuyere provided with such colder air, due to the fact that the coke is undercooled and is even less intensively burned because of the small quantity of air supplied thereto.

The cooling of the air is, in such a case, not only simply proportional to the length of the air path, but is further increased by virtue of the fact that the total quantity of air in the upper chamber decreases from tuyere to tuyere while the radiation heat losses remain constant.

The disadvantageous temperature drop relationships may best be seen from the following example.

It is assumed that a two-chamber bustle pipe of the above described type, insulated with a slag wool layer 65 mm. thick, hasaradiating outer surface of 26.5 m), of which the upper chamber alone takes up 14 m.. At a hot air temperature of 500 C., the temperature of the outer wall of the insulated bustle pipe is about ,C. if the surrounding ambient temperature is approximately 20 C. With these relationships, the heat transfer coefficient will be found to be about 10.5 kcaL/mfih. C., whereby the heat loss is determined to be about 630 kcal./m. h.

The furnace required 2500 Nmfi/h. of air which was blown in through six tuyeres. chamber, the flow of air is uniformly distributed, so that the associated outer surface effects an overall air temperature drop of approximately 9 C. From the, air entry port of the bustle pipe up to the connecting flanges for the individual tuyeres, there obtain the following total temperature drops for the individual tuyeres:

TuyereNo 1 2 3 45 6 Temperature a e.) n 13 1e 19 24 25 TuyereNm, 1 2 3 4 5 6 Temperature drop C.) 3 8 A conventional bustle pipe, when operated with hot air, is, therefore, with respect to the temperature distribution, not less favorable than a two-chamber bustle pipe, but as is well known, the pressure distribution is bad.

It is, therefore, an important object of the present invention to provide a bustle or blast air supply pipe for blast furnaces which enables the disadvantages and drawbacks of heretofore known means of this type to be avoided.

Another important object of the present invention is to provide a structure of the class referred to hereinabove which greatly facilitates the attainment of uniform air pressure and flow characteristics at all the tuyeres of a blast furnace air supply.

Still another object of the invention is to provide means as aforesaid which ensure a symmetrical distribution of the blast air through the various tuyeres.

Yet another object of the present invention is the provision of a substantially annular blast furnace bustle pipe by means of which uniform temperatures of the blast air' at each tuyere are maintained so as to prevent the abovementioned under-cooling of the coke in the furnace.

It is still a further object of this invention to provide such a bustle pipe which takes up a minimum of space and requires only a minimum of material for its manufacture, thereby rendering it highly economical to produce, install and operate.

More particularly, the present invention is based on the fact that for attaining a symmetrical high temperature zone in a hot air operated blast furnace, it is necessary to obtain not only a uniform pressure distribution but also a uniform temperature distribution in the blast air supply.

For the pur ose of obtaining uniform temperature rela? tionships, the blast air, as in the case of a conventional bustle pipe, is divided into two equal streams which run in opposite directions about the furnace, and, according to the invention, each of these streams provides one half 7 of the air for each tuyere. In this manner, the air passing through each tuyere has traversed the entire bustle pipe.

Patented Mar. 1, "1960 In the lower annularv Q The different temperatures of the two streams of air are equalized by the turbulent mixing, action occurring in each tuyere.

The arrangement, according to the invention, requires the same amount of space as a conventional bustle pipe. In fact, an already existing bustle pipe can, by appropriate structural modifications, be transformed .into a bustle pipe constructed in accordance with the principles of the invention. The amount of structural materials required is found to be very small.

The foregoing objects and advantages of the present inventionwill become manifest from a consideration of the following detailed description of an illustrative embodiment thereof in conjunction with the accompanying drawing, in which:

Fig. 1 is a diagrammatic, partly sectional view of a bustle pipe constructed according to the present invention;

Fig. 2 is a developed sectional view taken along the line A--B in Fig. 1; I

Fig. 3 is a sectional view taken along the line CD in Fig. 2; and,

Figures 4 and 5 are detail views of the guide vanes.

Referring now more particularly to the drawing, the bustle pipe comprises an annular housing 1 which has, for example, a rectangular flow cross section (see 3) and is disposed concentrically with the blastfurnaceZ. The air inlet 3 merges with the bustle pipe housing 1 in such a manner that the inside surfaces thereof are provided with as large a radius of curvature R as possible. The transition curvature extends on each side, preferably up to the first of the tuyeres 4 which are spaced equiangu larly along the housing 1. A partition 5, which in development has the form of an isosceles triangle (see Fig. 2), extends centrally through the housing 1 so as to divide the normal flow path defined within the interior of the housing into two parts or sections 1a and 1b which are adapted to be traversed in opposite directions by the blast air. Provided at the elevation of and coextensively with the air inlet means 3 are guide vanes 6, which may be and the curvatures of which are specifically designed to impart to the air the desired directions of flow, as will appear more fully hereinafter.

Attached to the upper edges of the partition 5, i.e., to the legs of the triangle, are metal sheets or plates 7 and 8, respectively, which extend substantially at right angles to the plane (as developed) of the partitions and to opposite sides thereof. The outer lateral edges of the metal members 7 and 8 are connected with respective side walls of the housing 1, while the edges 7a and 8a of these members located in aligned condition at the center of the partition, i.e., the apex of the triangle, are connected to the upper wall of the housing 1 at a point diametrically opposite the air inlet 3. From this point the members 7 and 8 extend in opposite directions substantially up to the air inlet 3, terminating in edges 7b and 8b, respectively. Each of the metal sheets or transverse partition members 7 and 8 is employed to block the entrance to one end of a respective one of the two flow path sections 1a and lb. The members 7 and 8 are shown in Fig. 2 in the form of inclined, straight, and plane members, for the purpose of gradually varying the cross-sections of the flow path sections In and 1b, but they may with advantage also he stepped from one tuyere region to the next.

The locus of the axes or centers of the tuyeres 4 coincides with the plane of the partition 5, the lower edge of which, i.e., the base of the triangle, rests on the bottom wall of the housing in which the tuyeres are formed. Consequently, one half of each tuyere is associated and in direct communication with a respective one of thetwo flow path sections. Thus,'one of the guide vanes 6directs some of the air from the inlet 3 into the How path section In, while the otherguidevane 6 directsanother portion of this air into the flow path section 1b. In this manner,-eaeh tuyere -4 obtains one half of the required quantity of air 'via' a relatively shorter flow path and the other half over a correspondingly and complementarily longer flow path. The temperature drop of the air is, of course, proportional to the length of the flow path, since the velocity of flow remains constant. As a result, there is obtained in all of the tuyeres 4' a predetermined temperature of the mixed air because, when viewed as an entity, the total flow path length from the air inlet 3 to each of the tuyeres is the same. Since thetwo streams of air fiow'in opposite directions,-there arises in each of the tuyeres a slight rotary motion or turbulence which brings about an immediate equalization of the temperature of the air in the particular tuyere due to the mixing of the two streams therein.

Because the cross-section of each of the two flow paths decreases with the length thereof, the same velocity of flow relationships are obtained in all the tuyeres, which ensures that a uniform supply of air is fed to the individual tuyeres.

By way .of rsum, therefore, it will be seen that in accordance with the present invention there has been provided a bustle pipe for blast furnaces, which bustle pipe comprises a housing, an air inlet to said housing, a plurality of tuyeres for blasting air from said housing into an associated blast furnace, and means, to wit, the partition 5 and its associated elements 7 and 8, located within the housing and along the path of flowof air therethrough for gradually changing the cross-section of the flow path in accordance :with the quantity of air passing each predetermined region of said housing, to thereby insure that the air has the same velocity of flow at each tuyere. As can be readily seen from the drawing, the partition 5 is disposed substantially vertically with respect to the plane of the inlets to the tuyeres 4 and extends centrally through the housing '1 and along the locus of the centers of the tuyeres. This construction divides the flow path entity into two oppositely directed parts as a result of which one half of the quantity of air passing through any one tuyere has flowed over a relatively short path from the air inlet 3, while the other half of this quantity of air has flowed over a complementarily longer path from said air inlet.

Having thus particularly described the invention, what is claimed and sought to be secured by Letters Patent is:

1. In a bustlepipe for blast furnaces, said bustle pipe including an annular housing having overall a substantially constant cross-section, an air inlet to said housing, and a plurality of tuyeres for blasting air from said housing into an associated blast furnace; theimprovement comprising means located in said housing and dividing said housing in two snail-shell-formed chambers with opposite windings and along the circumference ofsaid annular housing gradually changing the cross-sections of said chambers in accordance with the quantity of air divided in two streams and passing through said housing, so as to ensure that both streams of said air have the same velocity of flow but in opposite directions at each of said tuyeres, whereby each of said tuyeres is traversed by a quantity of air one-half of which has reached the said tuyere from said inlet via a relatively short path, and the other half of which has reached the said tuyere from said inlet via a correspondingly and complementarily longer path.

2. Ina bustle pipe said bustle pipe including a housing having overall a substantially constant cross-section, an air inlet to said housing, and a plurality of tuyeres for blasting air from said housing into an associated blast furnace; the improvement including means' located in said housing and along the path of flow of air therethrough for gradually changing the cross-section of said flow path inaccordance with the .quantity of air passing through: said housing, so as to ensure thatsaid air has the same velocityof flow :at each-of said tuyeres, said means comprising a partition located centrally of said housing and along the locus of the centers of said tuyeres to thereby divide the interior .of said housing into two sections defining in the same two oppositely directed parts of said flow path, whereby each of said tuyeres is traversed by a quantity of air one half of which has reached the said tuyere from said air inlet via a relatively short path, and the other half of which has reached the said tuyere from said inlet via a correspondingly and complementarily longer path.

3. In a bustle pipe according to claim 2; said partition comprising a central portion cylindrically formed and disposed coincidingly with respect to the longitudinal axes of said tuyeres, and two lateral portions extending transversely from said central'portion in opposite directions, to thereby form said oppositely directed parts of said flow path.

4. In a bustle pipe according to claim 3; a plurality of guide vanes operatively mounted in said housing at said air inlet, each of said guide vanes having a curvature matched with the curvature of the interior of said housing at that location to effect the desired deviation of air into said parts of said flow path.

5. In a bustle pipe according to claim 4; the transition portions of said housing extending from said air inlet to the initial ones of said tuyeres having radii of curvature as large as possible between the air inlet and said initial one of the tuyeres.

6. A bustle pipe for use in connection with a blast furnace, comprising an annular housing provided with an air inlet, a plurality of tuyeres disposed at equiangular locations insaid housing for blasting air into a blast furnace associated therewith, a cylindrical partition located within said housing substantially centrally thereof and along the locus of the centers of said tuyeres and substantially coinciding to the longitudinal axes of said tuyeres, said partition when viewed in flat condition having the shape of an isosceles triangle the base of which is in immediate proximity to said tuyeres, a pair of transverse partition members extending, respectively, in opposite directions from those edges of said partition constituting the legs of the triangle to thereby form within said housing two flow path sections each communicating directly with one half of each of said tuyeres, and a pair of guide vanes disposed within said housing between said air inlet and the initial parts of said flow path sections to direct a part of the air from said inlet into each of said flow path sections.

References Cited in the file of this patent UNITED STATES PATENTS 2,668,048 Ronceray Feb. 2, 1954 

